Ecological yield is the harvestable population growth of an ecosystem. It is most commonly measured in forestry: sustainable forestry is defined as that which does not harvest more wood in a year than has grown in that year, within a given patch of forest. However, the concept is also applicable to water, soil, and any other aspect of an ecosystem which can be both harvested and renewed—called renewable resources. The carrying capacity of an ecosystem is reduced over time if more than the amount which is "renewed" (refreshed or regrown or rebuilt) is consumed.